1. Industrial Field of the Invention
The present invention relates to an absorption chiller and more particularly, to a large-tonnage absorption chiller suitable for the district cooling system.
2. Description of the Prior Art
There have been publicly known arts, for example, as shown in Japanese Patent Unexamined Publication No. 2-078866 and No. 3-095364. The conventional arts individually employ a method of flowing chilled water through chillers in series, flowing cooling water through chillers in parallel, or spraying absorption solution in a plurality of stages in an absorber. However, an absorption chiller comprising a plurality of chiller units connected to each other, has not been publicly known, in which chilled water flows through the chiller units in series while cooling water flows through the chiller units in parallel, directions of flow of the chilled water and the cooling water are longitudinally reverse to each other in one chiller unit including a final outlet for the chilled water or the plurality of chiller units, and in the absorber in each chiller unit, absorption solution is sprayed in a plurality of stages.
When a scale of an absorption chiller is enlarged, flow rates of chilled water and cooling water are naturally increased and accordingly, the capacity of the transportation pump, sizes of pipes and the size of the cooling tower must be increased. An absorption chiller of a large scale is often used for district cooling system and installed in an overpopulated city for this purpose. Accordingly, it suffers various limitations concerning an installation space or a space where it occupies in a building or a certain place. In this connection, not only the chiller but also the whole plant including incidental equipments are required to be made compact. As for the chilled water, by setting the temperatures at the inlet and the outlet at 13.degree. C. and 6.degree. C., respectively, a difference of which is 1.4 times larger than that in the conventional machine in which the temperatures at the inlet and the outlet are set at 12.degree. C. and 7.degree. C., respectively, it is possible to reduce the amount of the chilled water to 70% of that in the conventional machine. As for the cooling water, by setting the temperatures at the inlet and the outlet at 32.degree. C. and 40.degree. C. respectively, a difference of which is 1.33 times larger than that of the prior art in which the temperatures at the inlet and the outlet are respectively set at 32.degree. C. and 38.degree. C., it is possible to reduce the amount of the cooling water to 75% of that in the conventional machine. However, any of the above temperature modifications makes it difficult for the chiller to fully carry out its performance. Further, a requirement for size reduction by about 20% to 25% of the conventional chiller is not satisfactorily fulfilled. In this connection, there occurs a necessity for some countermeasures of overcoming the problems.
In the case where the chiller is increased in size, it becomes impossible to transport the chiller as it is so that the chiller must be separated for transportation. On the other hand, the absorption chiller is sealingly charged with a lithium bromide solution which conspicuously corrodes iron under an oxygenic atmosphere. In order to prevent an inner side of the chiller from corrosion, it is necessary to maintain the inside of the chiller in a vacuum state. It is therefore the most important matter to separate the chiller while maintaining the inside of the chiller in a vacuum state in order to retain a reliability of the absorption chiller.